Fibrous material and method and apparatus for packaging the same



June 26, 1962 w G. VAN BECKUM ET AL 3,040,882

FIBROUS MATERIAL AND METHOD AND APPARATUS FOR PACKAGING THE SAME Filed 001;. 6, 1955 STEAM AJ/e la MOISTAIR HOZDRYA/R 2 27 STEAM /7 I 25 k VOL FEEDER DRYER /3 i 29 2e C'YCL ONE Ba /4 SEPARATOR MOIST AIR 46 M0137- AIR MOIST AIR fili 49 139 50" H07; DRY MOIST I107; DRY MOIST AIR AIR 45 AIR Am E IIOPPE L IN VEN TORS WILLIAM G! VI4IV BA'C'Kl/M BBQ/V J. THOMPSON A TTORIVE Y nite fitats 3,040,882 FIBROUS MATERIAL AND METHOD AND AP- PARATUS FOR PACKAGING THE SAME William G. Van Becknm, San Mateo, and Don J.

Thompson, Scotia, Califi, assignors to The Pacific Lumher Company, San Francisco, Calif., a corporation of Maine Filed Oct. 6, 1955, Ser. No. 538,992 8 Claims. (Cl. 206-835) This invention relates to improvements in fibrous material derived from wood and other sources and to improvements in methods and apparatus for producing such fibrous material. More particularly this invention relates to fibrous materials prepared from wood chips or the like by a process wherein the naturally compacted, relatively dense fibers are separated into a loose fibrous mass consisting of individual fibers and small bundles of fibers.

Fibrous materials of this general character are available from many sources. Some, as in the case of cotton, are already in a loose, flocculent condition. Other sources of fibrous materials, such as wood, contain the fibers in dense compacted form from which individual fibers or small bundles of fibers have been produced by such methods as shredding bark (which is relatively easily reduced to a loose, fibrous condition by mechanical shredding) and by a more complex process of shredding wood (which is more dense than bark and more resistant to shredding).

Wood has, for some years, been reduced to a loose, fibrous conditions by a process in which the wood is chipped and the chips are subjected to the action of steam at high temperature and pressure, for example, steam at 600 lbs. per square inch. I The steam impregnated chips are then blown into a chamber at atmospheric pressure. By reason of the softening efiect of steam, which penetrates the wood chips during the steaming or cooking process, and explosion of the mass upon sudden release of pressure the dense wood of the chips is converted to a mass of individual fibers and bundles of fibers which, upon drying, yield a loose, flocculent, very low density, fibrous mass.

All such fibrous materials has as a valuable property a very low density, a great bulk and a large percentage of voids. Such material is useful, among other things, for use as insulation material, in which case the low bulk and high percentage of voids impart valuable insulating properties.

A somewhat different utilization of such fibrous materials consists in their addition to drilling muds to prevent or inhibit circulation loss. As is well known in the oil and gas well drilling industry, drilling muds are employed which consist primarily of a colloidal material such as bentonite dispersed in Water, to which materials such as barytes are added to impart such properties as high density, etc. Drilling muds are used in large, frequently enormous quantity during the drilling of oil and gas wells to lubricate the drill bit, to float the cuttings up to the surface of the well and to hold back gas and/or oil pressures. Frequently during drilling a porous formation is encountered and the drilling mud leaks out from the well into the formation, resulting in what is known as circulation loss. Such circulation loss results not only in the rapid loss of a large quantity of relatively costly drilling mud but it also may require shut down of the drilling operation until the condition is corrected.

Many materials have been used or proposed for use to add to drilling muds when circulation loss is noted, to stop the same. Many of these materials are of fibrous nature, such as fiberized wood chips produced with steam in the manner described hereinabove. Other materials of a Patented June 26, 1962 ice nonfibrous or less clearly fibrous nature, such as cottonseed hulls, are also employed for this purpose.

Fibrous materials employed for such purposes are preferably in a very loose, low density state. More particularly, the individual fibers and small fiber bundles should be separated from one another, and the natural resiliency of these fibers and fiber bundles should be such that they are all separate, one from another; will flow easily from a container such as a paper bag into an insulating space, or a tank of drilling mud, or elsewhere; and are easily separated into a uniform mass of fibers of low density lacking localized areas of high density, due to compacted layers or clusters of fibers.

A problem encountered in the handling and storage of such fibrous materials is that they must be. compacted in the form of bales, or compressed into containers such as paper sacks for convenience and economy of shipment and storage. Yet, when the product is ready for use, e.g., as an insulation material or a circulation loss inhibitor, the compacted, compressed fibers must be separated and their low density, large bulk and large percentage of voids must be restored. Compression and compaction of fibers by the methods used heretofore destroys the natural resiliency of fibers, such that when a bale or sack is opened, the mass of fibrous material fails to assume its original bulk; i.e., the fibers and fiber bundles adhere together. The original bulk and looseness can be restored by tedious mechanical separation of the fibers, but to our knowledge no means has been provided heretofore whereby loose, fibrous material can be compressed or compacted into bales or containers, yet will not lose its natural resiliency and require tedious mechanical separation of the fibers.

By way of illustration, cotton is a loose, fibrous material as it exists in the boll and after it is separated from the seeds in a gin. When it is baled, however, as is required for storage and shipment, the cotton fibers lose their resilience and the mass loses its loose fluffy character, even after the bale is opened. This presents no problern in a textile mill where cotton is spun into threads, because techniques and apparatus are available to separate the cotton fibers to the desired degree of individuality and looseness.

By way of contrast, in oil and gas fields located at remote sites, the need for a circulation loss material is frequently an emergency need arising, perhaps, late at night. The drilling foreman must add circulation loss material as quickly as possible so as not to lose drilling mud and drilling time. Obviously, under controlled conditions such as prevail in a textile mill, baled cotton or other baled fibrous material can be used without undue difficulty, but under the conditions prevailing in oil and gas well drilling operations, it is highly inconvenient, in an emergency situation, if baled or sacked fibrous mate'- rial must be separated by hand before it can be added to the mud to function efiiciently as a circulation loss inhibitor.

A need, therefore, exists for a fibrous material in compacted form suitable for shipment and storage, yet has not lost the natural resiliency of its fibers, and'which is capable of resuming a loose, fibrous character with ease and without tedious hand or mechanical separation.

It is an object of the present invention to provide fibrous material in compacted form suitable for storage and shipment which has, however, a resilient quality remaining in the fibers and fiber bundles such that the mass of fibers can be separated readily when the compacting pressure is released.

It is a further object of the invention to provide a process whereby such fibrous material having loose, high bulk, low density properties as described hereinabove, can be packaged in relatively compact form suitable for shipment and storage, such process being of a character that it will not destroy the resilient properties of the fibers and fiber bundles, whereby when the compacting pressure is relieved the mass of fibers can be separated easily and caused to resume a loose, fiocculent form.

A still further object is to provide apparatus capable of carrying out the process as described hereinabove.

These and other objects of the invention will be apparent from the ensuing description and the appended claims.

In accordance with the present invention a fibrous material is provided in loose, uncompacted form such as desired for its final utilization as, for example, for insulation purposes or for inhibiting circulation loss; this fibrous material is dried, if necessary, to a sufficient dryness to prevent adhesion of the fibers and. the fiber bundles to one another under compacting pressure; a large quantity of the prepared loose fibrous material is charged to an elongated container, preferably of the same cross section as the container or envelope which is to contain the packaged, compacted product; the mass of fibers in the elongated container is compressed to the final packaged volume by a single compression stroke; and the envelope is sealed or closed to retain the entire mass of fibrous material in the desired compacted state.

This process may be applied to any fibrous material, for example, to shredded bark of trees such as Pacific Coast redwood and to the fibrous material produced from the wood of Pacific Coast redwood, Douglas fir, spruce, Southern pine, hemlock, etc.

In its preferred embodiment the starting material consists of wood chips, for example, chips of redwood, Douglas fir, spruce, Southern pine, hemlock, etc. Such chips are subjected to the steam cooking and explosion operation referred to hereinabove; the steamed or cooked material is then blown, i.e., it is expelled by the steam pressure through an orifice into an area of atmospheric pressure to explode the mass of consolidated fibers and produce a much greater volume of separate fibers; the fibers are then separated from steam and are dried so as to contain not more than about l214% by weight of moisture .as determined by standard oven drying technique; and the FIGURE of the drawings, which is a diagrammatic representation of the complete process commencing with the supply of chips to the steam gun and terminating with the sacked product.

Referring to the drawings, chips are shown at contained in a hopper 11. That is to say, logs, after the bark has been removed, are chipped by any suitable means to produce chips of suitably small size, such as customarily used in manufacture of paper pulp. About square chips are suitable.

The chips 10 in the hopper 11 are charged from time to time, vi.e., once during each cycle of operation, to a steam gun 12. Steam is supplied at about 200 p.s.i., through a line 13 containing a valve 14. Then steam at about 600 p.s.i. is supplied to the steam gun 12 through a line 13a containing a valve 14a. This high pressure steam is admitted until a gauge (not shown) shows that the pressure in the gun has risen to about 600 p.s.i. The

time required for the steam pressure in the gun 12 to reach 600 p.s.i. will vary, e.g., from /2 to 2 minutes. Thus, wet chips require more time than dry chips. When the pressure reaches 600 p.s.i., a slotted orifice 15 at the narrow tapered end of the gun 12 is opened to allow the high 4- pressure steam within the gun to expel the fibrous mixture through the orifice 15 and a line 16 into a cyclone separator 17. This step is known as blowing. Steam and air are separated from the fibers in the cyclone 17 through an outlet 18. The separated fibers then pass through a line 19 to a volumetric feeder 20 which feeds the separated fibers through a line 25 to a dryer 26. The dryer 26 is supplied with hot, dry air through an inlet line 27 which flows countercurrently to the fibers. Moisture-laden air is vented through an outlet line 28. The partly dried fibers then pass through a line 29 to a second cyclone 3t). Moist air is is vented through an outlet line 31 and the separated fibrous material passes through a line 32 to a second dryer 33 which is supplied with hot, dry air through an inlet line 35. Moist air is vented through a line 36. The fibrous material and moist air then passes through a line 37 to a third cyclone separator 38 wherein moist air is separated and vented through a line 39. The separated fibers pass through a line 45 to a third dryer 46 which is supplied with hot, dry air through a line 47. Moisture-laden air is vented through a line 48. Fibrous material and moist air then pass through a line 49 to a fourth cyclone 50. Air is vented at 51 and dry fibers pass through a line 52 to a hopper 53.

From the hopper 53 the dry fibrous material containing not more than about 12 to 14% moisture is supplied continuously to the upper reach of a continuous conveyor 54 and is continuously dumped by the conveyor into a ramming device which is generally indicated by the reference numeral 55. The ramming device 55 comprises two chutes 60A and 6013 which are of very great length (e.g., 25 to 30 feet for a 40 pound sack) and which have a common inlet or hopper 61, a gate valve 62 being provided which can assume either the position shown in solid lines or the position shown in broken lines to open either of the chutes 60A and 60B and to close the other. A ram 64 is provided for each of the chutes 60A and 60B which is fixed to the lower end of a rod 65 which is raised and lowered by any suitable means (not shown). To the lower end of each of the chutes 60A and 60B is fitted a sack 66, the bottom of which is supported by a plate 67 supported by a vertically movable rod or shaft 68. To clamp each sack to the lower end of its chute during filling, a pivoted clamp 69 is provided which is pivoted at 70 on a support 75 and is so weighted that its inner end will bear against the sack and hold the same firmly against the lower end of the chute.

In operation, dry fibrous material, which is shown at 63, is supplied continuously to the hopper portion 61 of the assembly 55, so that one or the other of the chutes 60A and 6GB is filling according to the position of the gate 62. Initially, the height of fibrous material loosely contained in a chute is determined which is required to fill a bag 66 when rammed into a bag. An operator notes when this height is reached, as by looking through a window in the chute which is filling, with the aid of a mirror. While one such chute is filling (e.g., the chute 66B), the operator will operate the ram 64 in the other chute by suitable control means (not shown). That is, the respective ram is caused to descend the length of a chute, thereby ramming all of the loose, fibrous material in the chute into the bag 66. The bag 66 is then detached from the chute by lowering the shaft 68 and plate 67 and it is then weighed and is closed by stapling or other suitable means. The closing operation is preferably carried out quickly; otherwise the resilient fiber will expand and spill out of the bag. Meanwhile, the other chute will have filled, the gate 62 is reversed and the procedure is repeated.

By the procedure thus described a suitably compacted mass of fibrous material is provided which will occupy a very small volume suitable for shipment and storage. Thus, paper bags of 4 cubic foot capacity may be filled with about 40 lbs. of fibrous material. Notwithstanding the compact form of the fibrous material, when these bags are opened, individual fibers retain their resilience; the material in an opened bag will gradually expand out of the bag; and the material does not require tedious mechanical or hand separation to loosen the fibers. When the fibrous mass is poured from a bag into drilling mud, the normal agitation of the drilling mud suifices to distribute the fibers uniformly. Likewise, the bags can be opened, the contents suplied to a conventional blowing and fluffing machine and blown into a form or space for holding insulation material.

Among factors which we have found to be important in producing a product of these characteristics, is the careful drying of the fibrous material so as to contain preferably not more than about 14%, most advantageously not more than about 12% moisture. If the moisture content exceeds about 14%, the fibers lose their resilience when compacted. Also the single continuous ramming operation is important, in which a chute is employed such as shown at 60A and 60B of sutficient length to hold all of the content of a bag, e.g., about 40 lbs., in loose, uncompacted condition, and in which the fibrous material is compacted by a single, continuous stroke. In prior practice, it has been customary to feed the fibrous material in several increments to a horizontal baler and to ram each increment, which becomes a distinct layer of densely compacted material. This procedure destroys the resiliency of the fibrous material, as shown by the inability of these layers to revert to their original loose, fluffy condition. The procedure of our invention does not destroy this resiliency.

The process and apparatus illustrated in the drawing are preferably used in conjunction with wood chips. However, other fibrous material may be employed. Where the fibrous material is already in loose, fiocculent condition, e.g., shredded bark, or ginned, unbaled cotton, the initial steaming and blowing operation may be omitted. Where the moisture content is initially low, the drying operation may be omitted.

Other apparatus may be used in place of that illustrated. Thus, the well known Asplund machine may be used instead of the Masonite type of gun shown at 12. As is well known in the pulp industry, the Asplund machine subjects chips to relatively low pressure (e.g., 150 p.s.i.) steam while conveyed by a screw conveyor, and it then subjects the steamed chips to mechanical disintegration between two discs, one of which rotates while the other remains stationary.

'It will, therefore, be apparent that a fibrous product having novel and very useful characteristics has been provided; and that a method and an apparatus for producing the same have also been provided.

We claim:

1. A wood derivative adapted for use as a circulation loss inhibitor comprisng separated fibers of wood, said fibers having a natural resilience which normally acts to maintain the fibers in a loose, fiocculent condition of low density and large volume, said fibers being in compressed form and packaged in an envelope and having a density several times greater and a Volume several fold less than the density and volume, respectively, of the fibers in their normal uncompressed state; said compressed fibers being further characterized by retention of their resilience under compression and by the property of expanding rapidly upon release of the compacting pressure to reassume a loose, flocculent condition.

2. The wood derivative of claim 1 in which the fibers contain not more than about 12% by weight of moisture.

3. The wood derivative of claim 2 in which the fibers are derived from the wood of Sequoia sempervirens.

4. The wood derivative of claim 1 in which the fibers contain not more than about 12% by weight of moisture and are derived from the wood of Sequoia sempervirens.

5. A method of producing a packaged circulation loss inhibitor adapted to be added to a drilling mud to inhibit circulation loss in the drilling of oil wells, said method comprising providing wood in the form of chips, fiberizing the chips by the action of steam to form a moist mass of fibers in a loose fiocculent condition, drying the moist fibers to reduce the moisture content thereof to a 14% maximum and form a volume of loose dry fibers, then providing an envelope for the fibers. having a volume several fold smaller than the volume of loose, dry, uncompressed fibers, ramming the volume of loose, dry, uncompressed fibers into said envelope by a continuous stroke to a degree of compression which will retain the property of the fibers expanding rapidly upon release of the compacting pressure to reassurne a loose, flocculent condition, and then closing the envelope.

6. The method of claim 5 in which the chips are fiberized by subjecting them to the action of steam at a high pressure and then releasing the chips suddenly to explode and fiberize the chips.

' 7. The method or" claim 6 in which the moist fibers resulting from exploding the chips are dried to a moisture content not more than about 12% by weight.

8. The method of claim 7 in which the chips are chips of S eqltoia sempervirens.

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